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Diffstat (limited to 'arch/sparc/math-emu/math_32.c')
| -rw-r--r-- | arch/sparc/math-emu/math_32.c | 515 |
1 files changed, 515 insertions, 0 deletions
diff --git a/arch/sparc/math-emu/math_32.c b/arch/sparc/math-emu/math_32.c new file mode 100644 index 000000000..d5beec856 --- /dev/null +++ b/arch/sparc/math-emu/math_32.c @@ -0,0 +1,515 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * arch/sparc/math-emu/math.c + * + * Copyright (C) 1998 Peter Maydell (pmaydell@chiark.greenend.org.uk) + * Copyright (C) 1997, 1999 Jakub Jelinek (jj@ultra.linux.cz) + * Copyright (C) 1999 David S. Miller (davem@redhat.com) + * + * This is a good place to start if you're trying to understand the + * emulation code, because it's pretty simple. What we do is + * essentially analyse the instruction to work out what the operation + * is and which registers are involved. We then execute the appropriate + * FXXXX function. [The floating point queue introduces a minor wrinkle; + * see below...] + * The fxxxxx.c files each emulate a single insn. They look relatively + * simple because the complexity is hidden away in an unholy tangle + * of preprocessor macros. + * + * The first layer of macros is single.h, double.h, quad.h. Generally + * these files define macros for working with floating point numbers + * of the three IEEE formats. FP_ADD_D(R,A,B) is for adding doubles, + * for instance. These macros are usually defined as calls to more + * generic macros (in this case _FP_ADD(D,2,R,X,Y) where the number + * of machine words required to store the given IEEE format is passed + * as a parameter. [double.h and co check the number of bits in a word + * and define FP_ADD_D & co appropriately]. + * The generic macros are defined in op-common.h. This is where all + * the grotty stuff like handling NaNs is coded. To handle the possible + * word sizes macros in op-common.h use macros like _FP_FRAC_SLL_##wc() + * where wc is the 'number of machine words' parameter (here 2). + * These are defined in the third layer of macros: op-1.h, op-2.h + * and op-4.h. These handle operations on floating point numbers composed + * of 1,2 and 4 machine words respectively. [For example, on sparc64 + * doubles are one machine word so macros in double.h eventually use + * constructs in op-1.h, but on sparc32 they use op-2.h definitions.] + * soft-fp.h is on the same level as op-common.h, and defines some + * macros which are independent of both word size and FP format. + * Finally, sfp-machine.h is the machine dependent part of the + * code: it defines the word size and what type a word is. It also + * defines how _FP_MUL_MEAT_t() maps to _FP_MUL_MEAT_n_* : op-n.h + * provide several possible flavours of multiply algorithm, most + * of which require that you supply some form of asm or C primitive to + * do the actual multiply. (such asm primitives should be defined + * in sfp-machine.h too). udivmodti4.c is the same sort of thing. + * + * There may be some errors here because I'm working from a + * SPARC architecture manual V9, and what I really want is V8... + * Also, the insns which can generate exceptions seem to be a + * greater subset of the FPops than for V9 (for example, FCMPED + * has to be emulated on V8). So I think I'm going to have + * to emulate them all just to be on the safe side... + * + * Emulation routines originate from soft-fp package, which is + * part of glibc and has appropriate copyrights in it (allegedly). + * + * NB: on sparc int == long == 4 bytes, long long == 8 bytes. + * Most bits of the kernel seem to go for long rather than int, + * so we follow that practice... + */ + +/* TODO: + * fpsave() saves the FP queue but fpload() doesn't reload it. + * Therefore when we context switch or change FPU ownership + * we have to check to see if the queue had anything in it and + * emulate it if it did. This is going to be a pain. + */ + +#include <linux/types.h> +#include <linux/sched.h> +#include <linux/mm.h> +#include <linux/perf_event.h> +#include <linux/uaccess.h> + +#include "sfp-util_32.h" +#include <math-emu/soft-fp.h> +#include <math-emu/single.h> +#include <math-emu/double.h> +#include <math-emu/quad.h> + +#define FLOATFUNC(x) extern int x(void *,void *,void *) + +/* The Vn labels indicate what version of the SPARC architecture gas thinks + * each insn is. This is from the binutils source :-> + */ +/* quadword instructions */ +#define FSQRTQ 0x02b /* v8 */ +#define FADDQ 0x043 /* v8 */ +#define FSUBQ 0x047 /* v8 */ +#define FMULQ 0x04b /* v8 */ +#define FDIVQ 0x04f /* v8 */ +#define FDMULQ 0x06e /* v8 */ +#define FQTOS 0x0c7 /* v8 */ +#define FQTOD 0x0cb /* v8 */ +#define FITOQ 0x0cc /* v8 */ +#define FSTOQ 0x0cd /* v8 */ +#define FDTOQ 0x0ce /* v8 */ +#define FQTOI 0x0d3 /* v8 */ +#define FCMPQ 0x053 /* v8 */ +#define FCMPEQ 0x057 /* v8 */ +/* single/double instructions (subnormal): should all work */ +#define FSQRTS 0x029 /* v7 */ +#define FSQRTD 0x02a /* v7 */ +#define FADDS 0x041 /* v6 */ +#define FADDD 0x042 /* v6 */ +#define FSUBS 0x045 /* v6 */ +#define FSUBD 0x046 /* v6 */ +#define FMULS 0x049 /* v6 */ +#define FMULD 0x04a /* v6 */ +#define FDIVS 0x04d /* v6 */ +#define FDIVD 0x04e /* v6 */ +#define FSMULD 0x069 /* v6 */ +#define FDTOS 0x0c6 /* v6 */ +#define FSTOD 0x0c9 /* v6 */ +#define FSTOI 0x0d1 /* v6 */ +#define FDTOI 0x0d2 /* v6 */ +#define FABSS 0x009 /* v6 */ +#define FCMPS 0x051 /* v6 */ +#define FCMPES 0x055 /* v6 */ +#define FCMPD 0x052 /* v6 */ +#define FCMPED 0x056 /* v6 */ +#define FMOVS 0x001 /* v6 */ +#define FNEGS 0x005 /* v6 */ +#define FITOS 0x0c4 /* v6 */ +#define FITOD 0x0c8 /* v6 */ + +#define FSR_TEM_SHIFT 23UL +#define FSR_TEM_MASK (0x1fUL << FSR_TEM_SHIFT) +#define FSR_AEXC_SHIFT 5UL +#define FSR_AEXC_MASK (0x1fUL << FSR_AEXC_SHIFT) +#define FSR_CEXC_SHIFT 0UL +#define FSR_CEXC_MASK (0x1fUL << FSR_CEXC_SHIFT) + +static int do_one_mathemu(u32 insn, unsigned long *fsr, unsigned long *fregs); + +/* Unlike the Sparc64 version (which has a struct fpustate), we + * pass the taskstruct corresponding to the task which currently owns the + * FPU. This is partly because we don't have the fpustate struct and + * partly because the task owning the FPU isn't always current (as is + * the case for the Sparc64 port). This is probably SMP-related... + * This function returns 1 if all queued insns were emulated successfully. + * The test for unimplemented FPop in kernel mode has been moved into + * kernel/traps.c for simplicity. + */ +int do_mathemu(struct pt_regs *regs, struct task_struct *fpt) +{ + /* regs->pc isn't necessarily the PC at which the offending insn is sitting. + * The FPU maintains a queue of FPops which cause traps. + * When it hits an instruction that requires that the trapped op succeeded + * (usually because it reads a reg. that the trapped op wrote) then it + * causes this exception. We need to emulate all the insns on the queue + * and then allow the op to proceed. + * This code should also handle the case where the trap was precise, + * in which case the queue length is zero and regs->pc points at the + * single FPop to be emulated. (this case is untested, though :->) + * You'll need this case if you want to be able to emulate all FPops + * because the FPU either doesn't exist or has been software-disabled. + * [The UltraSPARC makes FP a precise trap; this isn't as stupid as it + * might sound because the Ultra does funky things with a superscalar + * architecture.] + */ + + /* You wouldn't believe how often I typed 'ftp' when I meant 'fpt' :-> */ + + int i; + int retcode = 0; /* assume all succeed */ + unsigned long insn; + + perf_sw_event(PERF_COUNT_SW_EMULATION_FAULTS, 1, regs, 0); + +#ifdef DEBUG_MATHEMU + printk("In do_mathemu()... pc is %08lx\n", regs->pc); + printk("fpqdepth is %ld\n", fpt->thread.fpqdepth); + for (i = 0; i < fpt->thread.fpqdepth; i++) + printk("%d: %08lx at %08lx\n", i, fpt->thread.fpqueue[i].insn, + (unsigned long)fpt->thread.fpqueue[i].insn_addr); +#endif + + if (fpt->thread.fpqdepth == 0) { /* no queue, guilty insn is at regs->pc */ +#ifdef DEBUG_MATHEMU + printk("precise trap at %08lx\n", regs->pc); +#endif + if (!get_user(insn, (u32 __user *) regs->pc)) { + retcode = do_one_mathemu(insn, &fpt->thread.fsr, fpt->thread.float_regs); + if (retcode) { + /* in this case we need to fix up PC & nPC */ + regs->pc = regs->npc; + regs->npc += 4; + } + } + return retcode; + } + + /* Normal case: need to empty the queue... */ + for (i = 0; i < fpt->thread.fpqdepth; i++) { + retcode = do_one_mathemu(fpt->thread.fpqueue[i].insn, &(fpt->thread.fsr), fpt->thread.float_regs); + if (!retcode) /* insn failed, no point doing any more */ + break; + } + /* Now empty the queue and clear the queue_not_empty flag */ + if (retcode) + fpt->thread.fsr &= ~(0x3000 | FSR_CEXC_MASK); + else + fpt->thread.fsr &= ~0x3000; + fpt->thread.fpqdepth = 0; + + return retcode; +} + +/* All routines returning an exception to raise should detect + * such exceptions _before_ rounding to be consistent with + * the behavior of the hardware in the implemented cases + * (and thus with the recommendations in the V9 architecture + * manual). + * + * We return 0 if a SIGFPE should be sent, 1 otherwise. + */ +static inline int record_exception(unsigned long *pfsr, int eflag) +{ + unsigned long fsr = *pfsr; + int would_trap; + + /* Determine if this exception would have generated a trap. */ + would_trap = (fsr & ((long)eflag << FSR_TEM_SHIFT)) != 0UL; + + /* If trapping, we only want to signal one bit. */ + if (would_trap != 0) { + eflag &= ((fsr & FSR_TEM_MASK) >> FSR_TEM_SHIFT); + if ((eflag & (eflag - 1)) != 0) { + if (eflag & FP_EX_INVALID) + eflag = FP_EX_INVALID; + else if (eflag & FP_EX_OVERFLOW) + eflag = FP_EX_OVERFLOW; + else if (eflag & FP_EX_UNDERFLOW) + eflag = FP_EX_UNDERFLOW; + else if (eflag & FP_EX_DIVZERO) + eflag = FP_EX_DIVZERO; + else if (eflag & FP_EX_INEXACT) + eflag = FP_EX_INEXACT; + } + } + + /* Set CEXC, here is the rule: + * + * In general all FPU ops will set one and only one + * bit in the CEXC field, this is always the case + * when the IEEE exception trap is enabled in TEM. + */ + fsr &= ~(FSR_CEXC_MASK); + fsr |= ((long)eflag << FSR_CEXC_SHIFT); + + /* Set the AEXC field, rule is: + * + * If a trap would not be generated, the + * CEXC just generated is OR'd into the + * existing value of AEXC. + */ + if (would_trap == 0) + fsr |= ((long)eflag << FSR_AEXC_SHIFT); + + /* If trapping, indicate fault trap type IEEE. */ + if (would_trap != 0) + fsr |= (1UL << 14); + + *pfsr = fsr; + + return (would_trap ? 0 : 1); +} + +typedef union { + u32 s; + u64 d; + u64 q[2]; +} *argp; + +static int do_one_mathemu(u32 insn, unsigned long *pfsr, unsigned long *fregs) +{ + /* Emulate the given insn, updating fsr and fregs appropriately. */ + int type = 0; + /* r is rd, b is rs2 and a is rs1. The *u arg tells + whether the argument should be packed/unpacked (0 - do not unpack/pack, 1 - unpack/pack) + non-u args tells the size of the argument (0 - no argument, 1 - single, 2 - double, 3 - quad */ +#define TYPE(dummy, r, ru, b, bu, a, au) type = (au << 2) | (a << 0) | (bu << 5) | (b << 3) | (ru << 8) | (r << 6) + int freg; + argp rs1 = NULL, rs2 = NULL, rd = NULL; + FP_DECL_EX; + FP_DECL_S(SA); FP_DECL_S(SB); FP_DECL_S(SR); + FP_DECL_D(DA); FP_DECL_D(DB); FP_DECL_D(DR); + FP_DECL_Q(QA); FP_DECL_Q(QB); FP_DECL_Q(QR); + int IR; + long fsr; + +#ifdef DEBUG_MATHEMU + printk("In do_mathemu(), emulating %08lx\n", insn); +#endif + + if ((insn & 0xc1f80000) == 0x81a00000) /* FPOP1 */ { + switch ((insn >> 5) & 0x1ff) { + case FSQRTQ: TYPE(3,3,1,3,1,0,0); break; + case FADDQ: + case FSUBQ: + case FMULQ: + case FDIVQ: TYPE(3,3,1,3,1,3,1); break; + case FDMULQ: TYPE(3,3,1,2,1,2,1); break; + case FQTOS: TYPE(3,1,1,3,1,0,0); break; + case FQTOD: TYPE(3,2,1,3,1,0,0); break; + case FITOQ: TYPE(3,3,1,1,0,0,0); break; + case FSTOQ: TYPE(3,3,1,1,1,0,0); break; + case FDTOQ: TYPE(3,3,1,2,1,0,0); break; + case FQTOI: TYPE(3,1,0,3,1,0,0); break; + case FSQRTS: TYPE(2,1,1,1,1,0,0); break; + case FSQRTD: TYPE(2,2,1,2,1,0,0); break; + case FADDD: + case FSUBD: + case FMULD: + case FDIVD: TYPE(2,2,1,2,1,2,1); break; + case FADDS: + case FSUBS: + case FMULS: + case FDIVS: TYPE(2,1,1,1,1,1,1); break; + case FSMULD: TYPE(2,2,1,1,1,1,1); break; + case FDTOS: TYPE(2,1,1,2,1,0,0); break; + case FSTOD: TYPE(2,2,1,1,1,0,0); break; + case FSTOI: TYPE(2,1,0,1,1,0,0); break; + case FDTOI: TYPE(2,1,0,2,1,0,0); break; + case FITOS: TYPE(2,1,1,1,0,0,0); break; + case FITOD: TYPE(2,2,1,1,0,0,0); break; + case FMOVS: + case FABSS: + case FNEGS: TYPE(2,1,0,1,0,0,0); break; + } + } else if ((insn & 0xc1f80000) == 0x81a80000) /* FPOP2 */ { + switch ((insn >> 5) & 0x1ff) { + case FCMPS: TYPE(3,0,0,1,1,1,1); break; + case FCMPES: TYPE(3,0,0,1,1,1,1); break; + case FCMPD: TYPE(3,0,0,2,1,2,1); break; + case FCMPED: TYPE(3,0,0,2,1,2,1); break; + case FCMPQ: TYPE(3,0,0,3,1,3,1); break; + case FCMPEQ: TYPE(3,0,0,3,1,3,1); break; + } + } + + if (!type) { /* oops, didn't recognise that FPop */ +#ifdef DEBUG_MATHEMU + printk("attempt to emulate unrecognised FPop!\n"); +#endif + return 0; + } + + /* Decode the registers to be used */ + freg = (*pfsr >> 14) & 0xf; + + *pfsr &= ~0x1c000; /* clear the traptype bits */ + + freg = ((insn >> 14) & 0x1f); + switch (type & 0x3) { /* is rs1 single, double or quad? */ + case 3: + if (freg & 3) { /* quadwords must have bits 4&5 of the */ + /* encoded reg. number set to zero. */ + *pfsr |= (6 << 14); + return 0; /* simulate invalid_fp_register exception */ + } + fallthrough; + case 2: + if (freg & 1) { /* doublewords must have bit 5 zeroed */ + *pfsr |= (6 << 14); + return 0; + } + } + rs1 = (argp)&fregs[freg]; + switch (type & 0x7) { + case 7: FP_UNPACK_QP (QA, rs1); break; + case 6: FP_UNPACK_DP (DA, rs1); break; + case 5: FP_UNPACK_SP (SA, rs1); break; + } + freg = (insn & 0x1f); + switch ((type >> 3) & 0x3) { /* same again for rs2 */ + case 3: + if (freg & 3) { /* quadwords must have bits 4&5 of the */ + /* encoded reg. number set to zero. */ + *pfsr |= (6 << 14); + return 0; /* simulate invalid_fp_register exception */ + } + fallthrough; + case 2: + if (freg & 1) { /* doublewords must have bit 5 zeroed */ + *pfsr |= (6 << 14); + return 0; + } + } + rs2 = (argp)&fregs[freg]; + switch ((type >> 3) & 0x7) { + case 7: FP_UNPACK_QP (QB, rs2); break; + case 6: FP_UNPACK_DP (DB, rs2); break; + case 5: FP_UNPACK_SP (SB, rs2); break; + } + freg = ((insn >> 25) & 0x1f); + switch ((type >> 6) & 0x3) { /* and finally rd. This one's a bit different */ + case 0: /* dest is fcc. (this must be FCMPQ or FCMPEQ) */ + if (freg) { /* V8 has only one set of condition codes, so */ + /* anything but 0 in the rd field is an error */ + *pfsr |= (6 << 14); /* (should probably flag as invalid opcode */ + return 0; /* but SIGFPE will do :-> ) */ + } + break; + case 3: + if (freg & 3) { /* quadwords must have bits 4&5 of the */ + /* encoded reg. number set to zero. */ + *pfsr |= (6 << 14); + return 0; /* simulate invalid_fp_register exception */ + } + fallthrough; + case 2: + if (freg & 1) { /* doublewords must have bit 5 zeroed */ + *pfsr |= (6 << 14); + return 0; + } + fallthrough; + case 1: + rd = (void *)&fregs[freg]; + break; + } +#ifdef DEBUG_MATHEMU + printk("executing insn...\n"); +#endif + /* do the Right Thing */ + switch ((insn >> 5) & 0x1ff) { + /* + */ + case FADDS: FP_ADD_S (SR, SA, SB); break; + case FADDD: FP_ADD_D (DR, DA, DB); break; + case FADDQ: FP_ADD_Q (QR, QA, QB); break; + /* - */ + case FSUBS: FP_SUB_S (SR, SA, SB); break; + case FSUBD: FP_SUB_D (DR, DA, DB); break; + case FSUBQ: FP_SUB_Q (QR, QA, QB); break; + /* * */ + case FMULS: FP_MUL_S (SR, SA, SB); break; + case FSMULD: FP_CONV (D, S, 2, 1, DA, SA); + FP_CONV (D, S, 2, 1, DB, SB); + case FMULD: FP_MUL_D (DR, DA, DB); break; + case FDMULQ: FP_CONV (Q, D, 4, 2, QA, DA); + FP_CONV (Q, D, 4, 2, QB, DB); + case FMULQ: FP_MUL_Q (QR, QA, QB); break; + /* / */ + case FDIVS: FP_DIV_S (SR, SA, SB); break; + case FDIVD: FP_DIV_D (DR, DA, DB); break; + case FDIVQ: FP_DIV_Q (QR, QA, QB); break; + /* sqrt */ + case FSQRTS: FP_SQRT_S (SR, SB); break; + case FSQRTD: FP_SQRT_D (DR, DB); break; + case FSQRTQ: FP_SQRT_Q (QR, QB); break; + /* mov */ + case FMOVS: rd->s = rs2->s; break; + case FABSS: rd->s = rs2->s & 0x7fffffff; break; + case FNEGS: rd->s = rs2->s ^ 0x80000000; break; + /* float to int */ + case FSTOI: FP_TO_INT_S (IR, SB, 32, 1); break; + case FDTOI: FP_TO_INT_D (IR, DB, 32, 1); break; + case FQTOI: FP_TO_INT_Q (IR, QB, 32, 1); break; + /* int to float */ + case FITOS: IR = rs2->s; FP_FROM_INT_S (SR, IR, 32, int); break; + case FITOD: IR = rs2->s; FP_FROM_INT_D (DR, IR, 32, int); break; + case FITOQ: IR = rs2->s; FP_FROM_INT_Q (QR, IR, 32, int); break; + /* float to float */ + case FSTOD: FP_CONV (D, S, 2, 1, DR, SB); break; + case FSTOQ: FP_CONV (Q, S, 4, 1, QR, SB); break; + case FDTOQ: FP_CONV (Q, D, 4, 2, QR, DB); break; + case FDTOS: FP_CONV (S, D, 1, 2, SR, DB); break; + case FQTOS: FP_CONV (S, Q, 1, 4, SR, QB); break; + case FQTOD: FP_CONV (D, Q, 2, 4, DR, QB); break; + /* comparison */ + case FCMPS: + case FCMPES: + FP_CMP_S(IR, SB, SA, 3); + if (IR == 3 && + (((insn >> 5) & 0x1ff) == FCMPES || + FP_ISSIGNAN_S(SA) || + FP_ISSIGNAN_S(SB))) + FP_SET_EXCEPTION (FP_EX_INVALID); + break; + case FCMPD: + case FCMPED: + FP_CMP_D(IR, DB, DA, 3); + if (IR == 3 && + (((insn >> 5) & 0x1ff) == FCMPED || + FP_ISSIGNAN_D(DA) || + FP_ISSIGNAN_D(DB))) + FP_SET_EXCEPTION (FP_EX_INVALID); + break; + case FCMPQ: + case FCMPEQ: + FP_CMP_Q(IR, QB, QA, 3); + if (IR == 3 && + (((insn >> 5) & 0x1ff) == FCMPEQ || + FP_ISSIGNAN_Q(QA) || + FP_ISSIGNAN_Q(QB))) + FP_SET_EXCEPTION (FP_EX_INVALID); + } + if (!FP_INHIBIT_RESULTS) { + switch ((type >> 6) & 0x7) { + case 0: fsr = *pfsr; + if (IR == -1) IR = 2; + /* fcc is always fcc0 */ + fsr &= ~0xc00; fsr |= (IR << 10); + *pfsr = fsr; + break; + case 1: rd->s = IR; break; + case 5: FP_PACK_SP (rd, SR); break; + case 6: FP_PACK_DP (rd, DR); break; + case 7: FP_PACK_QP (rd, QR); break; + } + } + if (_fex == 0) + return 1; /* success! */ + return record_exception(pfsr, _fex); +} |